audio/blucli: New Port: BluOS CLI (blu) for Bluesound/NAD BluOS players

Features:

• Discovery: mDNS (_musc/_musp/_musz/_mush) + LSDP fallback (blu devices)
• Device selection: --device, BLU_DEVICE, config default_device, aliases, discovery names
• Playback: play/pause/stop/next/prev + play --url/--seek/--id
• Volume + modes: volume, mute, shuffle, repeat
• Grouping: group status|add|remove
• Queue/presets/browse: queue, presets, browse, playlists, inputs
• TuneIn: tunein search|play for quick "play X"
• Spotify Connect: spotify open (and optional Web API spotify login/search/play)
• Sleep timer: sleep
• Watch: long-poll Status / SyncStatus (watch status|sync)
• Scripting/safety: --json, --dry-run, --trace-http
• Diagnostics: diag, doctor, raw endpoint runner
• Shell completions: completions bash|zsh